Certain automotive components need to be held within a certain temperature range to operate correctly. In a vehicle powertrain, for example, one of these components is the vehicle's transmission that is used to transfer torque from the vehicle's engine to its wheels. It is known that operating a transmission at too high of a temperature can cause excessive wear, seals to harden and clutch performance to degrade, which shortens the life of the transmission. It is also known that transmissions will not operate as consistently, reliably and efficiently if they are too cold. Typically, it is desired to have the transmission operating temperature to be about the same as the engine's temperature and somewhere in the range of 160° to 200° Fahrenheit. Operation at the ideal temperature promotes optimized shift quality through stable viscosity and friction properties of the transmission's fluid. Additionally, the lower, controlled viscosity of the fluid resulting from a narrow operating temperature reduces viscous drag, improving transmission overall efficiency.
In an automatic transmission, automatic transmission fluid (ATF) serves as a coolant for the transmission while also lubricating transmission components and acting as the hydraulic fluid. Transmission fluid reduces heat and friction, which helps sustain an automatic transmission's life. Manual transmissions use a transmission oil sometimes referred to as gear oil. Modern attempts to control transmission temperature include oil cooling devices to cool down the transmission oil/fluid. Bypass valves may be used to bypass the cooling device when the oil/ATF drops below a certain temperature. Temperature rise times and the temperature achieved, however, are dependent upon the self-generated heat of the transmission. This is not a desirable mechanism since the source of the heat are the inefficiencies of the transmission. Modern transmissions have high efficiencies and forcing inefficient operation to generate heat reduces the benefit of controlled temperature operation.
Accordingly, there is a need and desire for an improved method and system for controlling the temperature of a powertrain component such as a transmission.